Haptic technology is on a roll; it's been adopted in more than 20 smartphone models, including the Nokia N8 and Samsung Galaxy S series, because it can help people interact with touch-screen applications more accurately and otherwise enhance the user experience, says Jennifer Colegrove, an analyst with DisplaySearch.

DisplaySearch, a Santa Clara, Calif.-based research firm that focuses on the display market, hasn't yet released growth projections for haptics, but Colegrove notes that tablet PCs are ripe for the technology. One tablet that already includes haptics is Samsung's Galaxy Tab, which has sold 2 million units since its launch in September of last year.

One practical application of haptics is, for example, to make the virtual keyboards on smartphones and tablets more usable. "The loss of tactile feedback [with virtual keyboards] tends to cause high error rates and user frustration," says Amritha Sridharan, an analyst at Frost & Sullivan. (See related story: "Will touch screens kill the keyboard?")

And emerging haptic feedback technologies can do a lot more than simply vibrate. They can make a display's surface feel rough like sandpaper, or slick, or wet. They might even create the sensation of something moving under your finger. Thanks to haptics, users will soon be able to experience a display surface as more than just a piece of glass.

On the downside, haptics work on top of touch screens, adding a layer to the display. That means there are two layers between the reader's eye and the media being displayed, which can reduce screen brightness.

Shaking up the display

Haptic systems deliver tactile feedback by using mechanical actuators and other mechanisms that cause the surface above the touch screen to vibrate. The simplest version of haptics is the familiar vibrate mode in a cell phone.

The technology has also expanded into consumer electronics, medical products and gaming, says Sridharan. As haptics become more sophisticated, she expects to see new applications in those areas, and in the automotive and home automation markets.

Immersion Corp.'s mechanical actuator system design dominates the market -- LG, Nokia and Samsung have together shipped nearly 200 million phones that use the technology designs it licenses, according to Dennis Sheehan, vice president of marketing for Immersion. Toshiba uses the technology in its dual-screen Libretto W100 concept laptop, and Synaptics uses it in its Fuse concept phone, which features touch dialing and navigation from the back of the device.

The concept behind Immersion's haptics is simple. Most cell phones already have a spinning motor with a slightly off-center weight attached that's used to create a vibration when the phone rings in silent mode. Immersion's software controls that motor to create different vibration patterns.

The current generation of smartphones built using Immersion's designs is limited to a few basic vibrational patterns capable of emulating a button click or a low-frequency woofer pattern to augment the bass sounds of a ring tone.

But Immersion and other haptics vendors are developing more sophisticated techniques that finely tune vibrational frequencies to simulate different textures on the screen surface, and to target specific areas of the screen so that, for example, only the finger touching a "depressed" key on a virtual keyboard feels a click sensation.

Immersion's newest "high-definition" system, called TouchSense 5000, use piezo actuators -- ceramic devices that move when current is applied -- to offer even more refined sensations. The company says that, by fine-tuning the vibrations in combination, its newest technology can cause the user to perceive that he's feeling different textures as he slides a finger over a display's surface, or it can create the sensation of motion, which could be useful for apps that involve the use of a virtual slider control.

The technology allows for vibrations that "more closely mimic" real-life sensations, according to Immersion. "For example, we have a pinball game application that when the ball travels over a metal grate, the haptics effects make it feel like the ball really is traveling over a metal grate," Sheehan says.

Even more refined sensations are possible. The combination of vibration and friction patterns required to emulate the feel of a wood-grain surface can be simulated using electromechanical actuators, Sheehan says. But the technology is costly to use in a smartphone. "We can't drop that into a $200 cell phone today, but it's coming," he predicts.

Therein lies the rub. TouchSense 5000 is available now, and Sheehan says several manufacturers are "actively evaluating" it. But no manufacturers have announced phones that use it or indicated when such devices might become available.

Immersion is also working with a partner to integrate its haptics technology with a "deformable surface" technology that allows sections of a touch screen to rise up or sink down in response to an electrical stimulus. For instance, individual keys could rise up and out of the screen's surface on top of the image of a virtual keypad or keyboard, further enhancing tactile feedback, Sheehan says. However, such shape-shifting display technology is still in the early stages of development.

Going big

Haptic designs based on actuators work well on small smartphone displays, but the component and drive electronics required are expensive to manufacture for the larger screens used in tablets and laptops.

Start-up Pacinian Corp. is working on a more scalable haptic technology, called surface actuation, that creates vibrations by applying an electrostatic field to two conductive surfaces that cover the touch screen. When activated by the touch of a finger, the top surface pulls away from the user's finger.

A force sensor can also detect the amount of pressure the user is applying to the screen and vary tactile feedback accordingly. Pacinian plans to leverage that capability to develop an ultrathin laptop keyboard that will still have low-profile physical keys but will be only half as thick as a traditional electromechanical keyboard.

Pacinian's technology can scale upward, but its systems are too large to fit into the small smartphone screens where Immersion dominates. Instead, the company has focused on developing tablet- and laptop-size screens of between six and 15 inches; it hopes to launch its first products, designed for use in industrial and medical systems, in the first half of this year, with products for the consumer market due by the first half of 2012.

Like Immersion's technology, Pacinian's haptics technology can vary vibrational frequencies to create the sensation that a touch-screen surface has a texture. However, Pacinian isn't "as focused on trying to create hundreds of different feels," says Mike Levin, vice president of business development at Spokane, Wash.-based Pacinian.

But that's exactly the focus of Senseg Ltd., a competing start-up. Its technology, like Pacinian's, is based on electrostatic fields, but instead of creating sensations when a user's finger presses the sensors' two layers together, Senseg's electrostatic field operates on the top surface, vibrating the user's finger and changing the friction between the finger and the surface.

The company claims that it can generate extremely refined textures, creating a range of touch sensations from sticky to slippery and from glass-smooth to sandpaper-rough. "We can replicate the pattern, using sets of frequencies, to synthesize texture, or a boundary, or something pulsating in your hand," says Ville Makinen, CEO of Helsinki, Finland-based Senseg.

Senseg breaks the haptic sensor area into a matrix of fingertip-size elements that it calls "pixels." Varying feedback between these pixels is what creates the sensation of movement under a finger or hand. Makinen says increasing pixel matrix densities will further refine the user sensation. Today, he says, "we can stimulate half of a finger, or just a portion of it."

While haptic technologies can approximate textures, not even Senseg's technology is going to give the full tactile feedback you'd experience by, say, touching a real cashmere sweater. When combined with visual and auditory input, however, haptics can enhance the touch-computing experience, says Makinen. "The important thing is the holistic experience. What you see, you also tend to feel."

Senseg says it's working with Toshiba but its technology has yet to be implemented in any commercially available products.

Coming soon to a device near you?

So far, even basic haptics technology hasn't caught on in a big way outside of smartphones, and more advanced haptics systems will take some selling. The challenge, says Sheehan, is convincing manufacturers that there's "sufficient value in the technology to adopt it in their devices."

Today, users don't see haptics alone as a selling point. "You're not going to go out there and say 'I need to get this phone because it has great haptics,'" says Tuong Nguyen, an analyst at Gartner. "It's not sexy."

But Andrew Hsu, technology strategist at touch-screen maker Synaptics, thinks that will change. Haptics could become a checklist feature in tablets and other mobile touch displays, just as multitouch interactivity is today, he says. In the future, he predicts, "if you have a touch-screen device and you don't have this technology, you'll feel that the device is broken."

That remains to be seen. But Nguyen says the technology will continue to make inroads in areas such as gaming, virtual worlds, training tools and simulation environments, and in smartphones, tablets and other mobile computing systems. The more sophisticated, high-definition haptics technologies might take another year or two to catch on and find their way down the cost curve.

But that could change overnight if a must-have mobile device popularizes it. "If the next iPhone has it, then everyone is going to have to have it," says Nguyen. "That was the case with multitouch. That is the case with gyroscopes, which Apple introduced with the iPhone 4. And that could be the case with haptics."

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